The mouth of the Hathpur (or Hathipol) Tunnel, Ramgarh, Chota Nagpur.

Photograph of the Hathpur tunnel taken by Joseph David Beglar c.1874-75 which forms part of the Archaeological Survey of India Collections (Indian Museum Series). The accompanying text explains that this site was, "Probably a natural fissure through which a small rivulet has worn a passage." Beglar claims that the tunnel was formed by the water of a lake which, needing an outlet, forced its way through the the spur of a hill at this point. The waters bored a tunnel four hundred and fifty feet in length through soft sandstone at one end. Wide at either end, the tunnel becomes quite narrow in the middle where the rock is described as "granitic" by Beglar.